This invention concerns a plant for multistrand straightening and cutting to length of rolled sections or bars. The plant concerns in particular the cutting to size of rolled section, such as angle irons, channel sections, T-bars, window profiles, trackways for lifts or elevators or the like, in cooperation with a straightening operation, such sections being different from rolled bars having a plain profile such as round and flat bars, etc.
In the description hereinafter we shall call the bars with a plain profile "rolled bars", whereas sections with a complex profile will be called "rolled sections".
Plants for straightening and cutting to size rolled sections and bars such as angle irons, channel sections, T-bars, window profiles, trackways for lifts or elevators and the like are known (see EP-A-No. 0,067,391). Such plants provide a straightening machine and, downstream thereof, a flying shears able to shear layers of rolled stock to size while moving.
However, these plants involve great problems in shearing rolled sections and therefore it is often referred to avoid shearing such sections to size in cooperation with the straightening operation.
These problems arise due to the fact that while rolled bars may be cut by means of normal (flying) shears, in the case of rolled sections, which have a relatively more complex profile, the use of special shears, specific to each kind of profile is required, in order to avoid the ends of the rolled sections to present deformations or burrs.
These problems become even worse when it is necessary to operate on layers of rolled sections, that is to say, when several rolled sections have to be straightened at one and the same time, as is required in the modern rolling art.
A plant according to such rolling art can be seen in document EP-A-No. 0,201,120, which discloses a procedure and a device to feed a multiple-feed straightening machine automatically downstream of a cooling plate.
This document does not mention the problems arising during the cutting operation of the rolled sections and may be only seen as a state of the art example in the field of rolling.
Document DE-C-No. 1,217,747 discloses a rolled conveyor feeding a straightening machine positioned on line with said conveyor, which is located aside of a cooling plate and cooperates therewith. A layer of rolled sections is moved from the cooling plate to the conveyor, where it is firstly clamped at one end, secondly clamped at the other end by means of jaws configured with the same shape of the rolled sections.
While the rolled sections are clamped, their ends are cropped by means of appropriate saws.
The layer of rolled sections passes then through the straightening machine, after which the rolled sections are distributed on two separate cutting conveyors, on which they are cut by means of shears.
Document EP-A-No. 0,067,391 discloses a development of the plant described in DE-C-No. 1,217,747, in that it provides a single flying shears.
In both cases the procedure is slow and complicated, especially in the case of DE-C-No. 1,217,747 where special clamping jaws are required, which must have the same shape as the rolled section. Some kinds of rolled sections, having a relatively complex profile, as T-bars, window profiles, or trackways for elevators, may not be correctly clamped.